Adrenal Scintigraphy

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It appears that this method can replace AVS, is that true:

Adrenal Scintigraphy. The widespread application of adrenal scintigraphy is limited by the lack of experienced nuclear medicine centers. In addition to anatomical localization, adrenocortical scintigraphy provides a functional characterization of the adrenals based on the uptake and accumulation in functioning adrenocortical tissues of radiotracers, such as iodocholesterol-labeled analogs (131 I-6--iodomethyl-19-norcholesterol [NP-59] and 75 Se-6--selenomethyl cholesterol). Hypersecreting tumors (eg, cortisol, aldosterone, and androgen secreting adenomas) and nonhypersecreting adenomas show radiocholesterol uptake, whereas primary and secondary adrenal malignancies appear as "cold" nodules. Incidentalomas may show different radiocholesterol uptake patterns related to their nature and functional status.

Adrenal medullary scintigraphy requires radioiodinated guanethidine analogs, 131I-MIBG and 123I-MIGB, which are specifically concentrated in the sympathomedullary system by the active high-affinity type 1 transport mechanism. 123I-MIGB scintigraphy localizes pheochromocytoma as focal increased adrenal uptake with 86% sensitivity and 99% specificity. Masses less than 1.5 to 2 cm in diameter and large tumors with extensive tumoral necrosis and/or hemorrhage may not show sufficient MIBG uptake for visualization. False-negative results also may be due to drugs that interfere with uptake. [Ref.]